A system and method for standoff detection of explosives and explosive residue. A laser light source illuminates a target area having an unknown sample producing luminescence emitted photons, scattered photons and plasma emitted photons. A first optical system directs light to the target area. A video capture device outputs a dynamic image of the target area. A second optical system collects photons, and directs collected photons to a first two-dimensional array of detection elements and/or to a fiber array spectral translator device which device includes a two-dimensional array of optical fibers drawn into a one-dimensional fiber stack. A spectrograph is coupled to the one-dimensional fiber stack of the fiber array spectral translator device, wherein the entrance slit of the spectrograph is coupled to the one dimensional fiber stack.
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31. A method comprising:
surveying an above ground area to identify a region of interest based on at least one of size, shape and color of the region of interest;
illuminating the region of interest with a plurality of photons to thereby produce emitted photons from the region of interest;
analyzing the emitted photons, produced by the region of interest, using fluorescence spectroscopy to produce at least one of the following: a plurality of spatially resolved fluorescence spectra and a plurality wavelength resolved fluorescence images;
using at least one of the following to identify a target area: the plurality of spatially resolved fluorescence spectra and the plurality wavelength resolved fluorescence images;
illuminating the target area with a plurality of photons to thereby produce raman scattered photons and plasma emitted photons from the target area;
collecting, via a fiber array spectral translator device, raman scattered photons and plasma emitted photons produced by the target area, wherein said device comprises a two dimensional array of optical fibers drawn into a one dimensional fiber stack so as to effectively convert a two-dimensional field of view into a curvilinear field of view;
analyzing the raman scattered photons, produced by the target area, using raman spectroscopy to produce a plurality of spatially resolved raman spectra;
analyzing the plasma emitted photons, produced by the target area, using laser induced breakdown spectroscopy to produce a plurality of spatially resolved atomic spectra; and
applying a fusion algorithm to at least two of the following to identify one or more chemical compounds in the target area: the plurality of spatially resolved fluorescence spectra, the plurality of spatially resolved raman spectra and the plurality of spatially resolved atomic spectra.
33. A method comprising:
surveying a subsurface area to identify a region of interest based on at least one of size, shape and color of the region of interest;
illuminating the region of interest with a plurality of photons to thereby produce reflected photons from the region of interest;
analyzing the reflected photons, produced by the region of interest, using near infrared spectroscopy to produce at least one of the following: a plurality of spatially resolved near infrared spectra and a plurality wavelength resolved near infrared images;
using at least one of the following to identify a target area: the plurality of spatially resolved near infrared spectra and the plurality wavelength resolved near infrared images;
illuminating the target area with a plurality of photons to thereby produce raman scattered photons and plasma emitted photons from the target area;
collecting, via a fiber array spectral translator device, raman scattered photons and plasma emitted photons produced by the target area, wherein said device comprises a two dimensional non-linear array of optical fibers drawn into a one dimensional fiber stack so as to effectively convert a two-dimensional field of view into a curvilinear field of view;
analyzing the raman scattered photons, produced by the target area, using raman spectroscopy to produce a plurality of spatially resolved raman spectra;
analyzing the plasma emitted photons, produced by the target area, using laser induced breakdown spectroscopy to produce a plurality of spatially resolved atomic spectra; and
applying a fusion algorithm to at least two of the following to identify one or more chemical compounds in the target area: the plurality of spatially resolved near infrared spectra, the plurality of spatially resolved raman spectra and the plurality of spatially resolved atomic spectra.
1. A system comprising:
a laser light source configured to illuminate a target area having an unknown sample, to thereby produce luminescence emitted photons, scattered photons and plasma emitted photons from different locations on or within the unknown sample;
a first optical system coupled to said laser light source to direct light to the target area having the unknown sample;
a video capture device that outputs a dynamic image of the target area;
a first two-dimensional array of detection elements;
a second optical system that collects said luminescence emitted, said scattered, and said plasma emitted photons, and directs the collected luminescence emitted photons to said first two-dimensional array of detection elements coupled to said second optical system and further directs the collected scattered and plasma emitted photons to a fiber array spectral translator device coupled to said second optical system;
wherein said first two-dimensional array detects in a spatially accurate manner said luminescence emitted photons received from said second optical system and generates at least one of the following:
a plurality of spatially resolved fluorescence spectra, and
a plurality of spatially accurate wavelength resolved fluorescence images;
wherein said fiber array spectral translator device outputs at least one of the following received from said second optical system:
said collected plasma emitted photons, and
said collected scattered photons,
and includes a two-dimensional array of optical fibers drawn into a one-dimensional fiber stack so as to effectively convert a two-dimensional field of view into a curvilinear field of view;
a photodiode coupled to said first optical system to generate a gating signal to synchronize an acquisition time of a second two dimensional array of detection elements with a pulse width of laser light emanating from said laser light source;
a spectrograph coupled to said one-dimensional fiber stack of said fiber array spectral translator device, wherein an entrance slit of the spectrograph is coupled to said one dimensional fiber stack to perform at least one of the following: disperse said scattered photons output by the fiber array spectral translator device to generate a plurality of spatially resolved raman spectra, and disperse said plasma emitted photons output by the fiber array spectral translator device to generate a plurality of spatially resolved atomic spectra; and
wherein said second two dimensional array of detection elements coupled to said spectrograph detects the plurality of spatially resolved raman spectra or the plurality of spatially resolved atomic spectra produced by said spectrograph.
11. A system comprising:
a laser light source configured to illuminate a target area having an unknown sample, to thereby produce scattered photons and plasma emitted photons from different locations on or within the sample;
a broadband light source that illuminates the sample with broadband light to thereby produce photons reflected from different locations on or within the unknown sample,
a first optical system coupled to said laser light source to direct light to the target area having the unknown sample;
a video capture device that outputs a dynamic image of the target area;
a first two-dimensional array of detection elements;
a second optical system that collects said reflected, said scattered, and said plasma emitted photons, and directs the collected reflected photons to said first two-dimensional array of detection elements coupled to said second optical system and further directs the collected scattered and plasma emitted photons to a fiber array spectral translator device coupled to said second optical system;
wherein said first two-dimensional array detects in a spatially accurate manner said reflected photons received from said second optical system to thereby generate one or more of: a plurality of spatially accurate wavelength resolved infrared images and a plurality of spatially resolved infrared spectra;
wherein said fiber array spectral translator device outputs at least one of the following received from said second optical system:
e####
said collected plasma emitted photons, and
said collected scattered photons,
and includes a two-dimensional array of optical fibers drawn into a one-dimensional fiber stack so as to effectively convert a two-dimensional field of view into a curvilinear field of view;
a photodiode coupled to said first optical system to generate a gating signal to synchronize an acquisition time of a second two dimensional array of detection elements with a pulse width of laser light emanating from said laser light source;
a spectrograph coupled to said one-dimensional fiber stack of said fiber array spectral translator device, wherein an entrance slit of the spectrograph is coupled to said one dimensional fiber stack to perform at least one of the following: disperse said scattered photons output by the fiber array spectral translator device to generate a plurality of spatially resolved raman spectra, and disperse said plasma emitted photons output by the fiber array spectral translator device to generate a plurality of spatially resolved atomic spectra; and
wherein said second two dimensional array of detection elements coupled to said spectrograph detects the plurality of spatially resolved raman spectra or the plurality of spatially resolved atomic spectra produced by said spectrograph.
21. A system comprising:
a laser light source configured to illuminate a target area having an unknown sample, to thereby produce luminescence emitted photons, scattered photons and plasma emitted photons from different locations on or within the sample;
a broadband light source that illuminates the sample with broadband light to thereby produce photons reflected from different locations on or within the unknown sample,
a first optical system coupled to said laser light source to direct light to the target area having the unknown sample;
a video capture device that outputs a dynamic image of the target area;
a first two-dimensional array of detection elements;
an infrared two-dimensional array of detection elements;
a second optical system that collects said luminescence emitted, said reflected, said scattered, and said plasma emitted photons, and directs the collected luminescence emitted photons to said first two-dimensional array of detection elements coupled, directs the collected reflected photons to said infrared two-dimensional array of detection elements coupled to said second optical system, and further directs the collected scattered and plasma emitted photons to a fiber array spectral translator device coupled to said second optical system;
wherein said first two-dimensional array detects in a spatially accurate manner said luminescence emitted photons received from said second optical system to thereby generate a plurality of spatially resolved fluorescence spectra;
wherein said infrared two-dimensional array detects in a spatially accurate manner said reflected photons received from said second optical system;
wherein said fiber array spectral translator device outputs at least one of the following received from said second optical system:
said collected plasma emitted photons, and
said collected scattered photons,
and includes a two-dimensional array of optical fibers drawn into a one-dimensional fiber stack so as to effectively convert a two-dimensional field of view into a curvilinear field of view;
a photodiode coupled to said first optical system to generate a gating signal to synchronize an acquisition time of a second two dimensional array of detection elements with a pulse width of laser light emanating from said laser light source;
a spectrograph coupled to said one-dimensional fiber stack of said fiber array spectral translator device, wherein an entrance slit of the spectrograph is coupled to said one dimensional fiber stack to perform at least one of the following: disperse said scattered photons output by the fiber array spectral translator device to generate a plurality of spatially resolved raman spectra, and disperse said plasma emitted photons output by the fiber array spectral translator device to generate a plurality of spatially resolved atomic spectra; and
wherein said second two dimensional array of detection elements coupled to said spectrograph detects the plurality of spatially resolved raman spectra or the plurality of spatially resolved atomic spectra produced by said spectrograph.
2. The system of
3. The system of
4. The system of
5. The system of
6. The system of
7. The system of
8. The system of
9. The system of
first control signals that control operation of the laser light source;
second control signals that control operation of the second optical system such that the second optical system directs the collected luminescence emitted photons to a filter and directs the collected scattered photons and the plasma emitted photons to the fiber array spectral translator device; and
third control signals that control operation of the filter such that the filter sequentially filters collected luminescence emitted photons, in each of a plurality of predetermined wavelength bands.
10. The system of
wherein, in said luminescence emitted mode, the first control signals control operation of the laser light source in order to produce luminescence emitted photons from different locations on or within the unknown sample, the second control signals control the operation of the second optical system such that the second optical system directs the collected luminescence emitted photons to the filter, the third control signals control operation of the filter such that the filter sequentially filters collected luminescence emitted photons, in each of a plurality of predetermined wavelength bands;
wherein, in said raman mode, the first control signals control operation of the laser light source in order to produce scattered photons from different locations on or within the unknown sample, the second control signals control the operation of the second optical system such that the second optical system directs the collected scattered photons to the fiber array spectral translator device; and
wherein, in said LIBS mode, the first control signals control operation of the laser light source in order to produce plasma emitted photons from different locations on or within the unknown sample, the second control signals control the operation of the second optical system such that the second optical system directs the collected plasma emitted photons to the fiber array spectral translator device.
12. The system of
13. The system of
14. The system of
15. The system of
16. The system of
17. The system of
18. The system of
19. The system of
first control signals that control operation of the laser light source and the broad band light source;
second control signals that control operation of the second optical system such that the second optical system directs the collected reflected photons to a filter and directs the collected scattered photons and the plasma emitted photons to the fiber array spectral translator device; and
third control signals that control operation of the filter such that the filter sequentially filters collected reflected photons, in each of a plurality of predetermined wavelength bands.
20. The system of
wherein, in said infrared mode, the first control signals control operation of the broadband light source in order to produce photons reflected from different locations on or within the unknown sample, the second control signals control the operation of the second optical system such that the second optical system directs the collected reflected photons to the filter, the third control signals control operation of the filter such that the filter sequentially filters collected reflected photons, in each of a plurality of predetermined wavelength bands;
wherein, in said raman mode, the first control signals control operation of the laser light source in order to produce scattered photons from different locations on or within the unknown sample, the second control signals control the operation of the second optical system such that the second optical system directs the collected scattered photons to the fiber array spectral translator device; and
wherein, in said LIBS mode, the first control signals control operation of the laser light source in order to produce plasma emitted photons from different locations on or within the unknown sample, the second control signals control the operation of the second optical system such that the second optical system directs the collected plasma emitted photons to the fiber array spectral translator device.
22. The system of
23. The system of
24. The system of
25. The system of
26. The system of
27. The system of
28. The system of
29. The system of
first control signals that control operation of the laser light source and the broadband light source;
second control signals that control operation of the second optical system such that the second optical system directs the collected reflected photons and the luminescence emitted photons to a filter and directs the collected scattered photons and the plasma emitted photons to the fiber array spectral translator device; and
third control signals that control operation of the filter such that the filter sequentially filters collected reflected photons and collected luminescence emitted photons, in each of a plurality of predetermined wavelength bands; and
fourth control signals that control operation of steering mirror such that the steering mirror directs the luminescence emitted photons to the first two dimensional array of detection elements and directs the reflected photons to the infrared two dimensional array of detection element.
30. The system of
wherein, in said luminescence emitted mode, the first control signals control operation of the laser light source in order to produce luminescence emitted photons from different locations on or within the unknown sample, the second control signals control the operation of the second optical system such that the second optical system directs the collected luminescence emitted photons to the filter, the third control signals control operation of the filter such that the filter sequentially filters collected luminescence emitted photons, in each of a plurality of predetermined wavelength bands, the fourth control signals such that a steering mirror directs the luminescence emitted photons to the first two dimensional array of detection elements;
wherein, in said infrared mode, the first control signals control operation of the broadband light source in order to produce photons reflected from different locations on or within the unknown sample, the second control signals control the operation of the second optical system such that the second optical system directs the collected reflected photons to the filter, the third control signals control operation of the filter such that the filter sequentially filters collected reflected photons, in each of a plurality of predetermined wavelength bands, the fourth control signals such that a steering mirror directs the reflected photons to the infrared two dimensional array of detection elements;
wherein, in said raman mode, the first control signals control operation of the laser light source in order to produce scattered photons from different locations on or within the unknown sample, the second control signals control the operation of the second optical system such that the second optical system directs the collected scattered photons to the fiber array spectral translator device, and
wherein, in said LIBS mode, the first control signals control operation of the laser light source in order to produce plasma emitted photons from different locations on or within the unknown sample, the second control signals control the operation of the second optical system such that the second optical system directs the collected plasma emitted photons to the fiber array spectral translator device.
32. The method of
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This application claims the benefit of U.S. Patent Application No. 60/699,251 filed Jul. 14, 2005 entitled SHIELD: Standoff Hyperspectral Imaging Explosives LIDAR Detector/Optical Standoff Detection of Explosive Residue, and U.S. Patent Application No. 60/786,978 filed Mar. 29, 2006 entitled Time and Space Resolved Standoff Hyperspectral IED Explosives LIDAR Detection (TSR-SHIELD).
This application relates generally to systems and methods for detection of explosive material and residue of explosive material.
The present disclosure provides for a system and method for standoff detection of explosives and explosive residue. A laser light source is configured to illuminate a target area having an unknown sample producing luminescence emitted photons, scattered photons and plasma emitted photons from different locations on or within the unknown sample. A first optical system is optically coupled to the laser light source to direct light to the target area having the unknown sample. A video capture device outputs a dynamic image of the target area. A second optical system collects the luminescence emitted, the scattered, and the plasma emitted photons, and directs the collected luminescence emitted photons to a first two-dimensional array of detection element. The second optical system further directs the collected scattered and plasma emitted photons to a fiber array spectral translator device. The first two-dimensional array of detection elements detects in a spatially accurate manner the luminescence emitted photons received from the second optical system and generates at least one of the following: a plurality of spatially resolved fluorescence spectra, and a plurality of spatially accurate wavelength resolved fluorescence images. The fiber array spectral translator device outputs at least one of the following received from the second optical system: the collected plasma emitted photons, and the collected scattered photons. The device includes a two-dimensional array of optical fibers drawn into a one-dimensional fiber stack so as to effectively convert a two-dimensional field of view into a curvilinear field of view. A photodiode is optically coupled to the first optical system and generates a gating signal to synchronize an acquisition time of a second two dimensional array of detection elements with a pulse width of the laser light emanating from the laser light source. A spectrograph is coupled to the one-dimensional fiber stack of the fiber array spectral translator device, wherein the entrance slit of the spectrograph is optically coupled to the one dimensional fiber stack. The spectrograph disperses the scattered photons output by the fiber array spectral translator device to generate a plurality of spatially resolved Raman spectra. It also disperses the plasma emitted photons output by the fiber array spectral translator device to generate a plurality of spatially resolved atomic spectra. The second two dimensional array of detection elements is optically coupled to the spectrograph and detects the plurality of spatially resolved Raman spectra and the plurality of spatially resolved atomic spectra produced by the spectrograph.
The present disclosure further provides for a method for detecting explosive material above ground. An above ground area is surveyed to identify a region of interest based on at least one of size, shape and color of the region of interest. The region of interest is illuminated with a plurality of photons to thereby produce emitted photons from the region of interest. The emitted photons, produced by the region of interest, are analyzed using fluorescence spectroscopy to produce at least one of the following: a plurality of spatially resolved fluorescence spectra and a plurality wavelength resolved fluorescence images. To identify a target area, the plurality of spatially resolved fluorescence spectra and the plurality wavelength resolved fluorescence images are used. The target area is illuminated with a plurality of photons to thereby produce Raman scattered photons and plasma emitted photons from the target area. Using a fiber array spectral translator device, Raman scattered photons and plasma emitted photons are collected. The device comprises a two dimensional non-linear array of optical fibers drawn into a one dimensional fiber stack that converts a two-dimensional field of view into a curvilinear field of view, wherein the one dimensional fiber stack is coupled to an entrance slit of an imaging spectrometer. The Raman scattered photons, produced by the target area, are analyzed using Raman spectroscopy to produce a plurality of spatially resolved Raman spectra. The plasma emitted photons, produced by the target area, are analyzed using laser induced breakdown spectroscopy to produce a plurality of spatially resolved atomic spectra. A fusion algorithm is applied to at least two of the following to identify one or more chemical compounds in the target area: the plurality of spatially resolved fluorescence spectra, the plurality of spatially resolved Raman spectra and the plurality of spatially resolved atomic spectra.
The present disclosure further provides for a method for detecting explosive material underground. An above ground area is surveyed to identify a region of interest based on at least one of size, shape and color of the region of interest. The region of interest is illuminated with a plurality of photons to thereby produce reflected photons from the region of interest. The reflected photons, produced by the region of interest, are analyzed using near infrared spectroscopy to produce at least one of the following: a plurality of spatially resolved near infrared spectra and a plurality wavelength resolved near infrared images. To identify a target area, the plurality of spatially resolved near infrared spectra and the plurality wavelength resolved near infrared images are used. The target area is illuminated with a plurality of photons to thereby produce Raman scattered photons and plasma emitted photons from the target area. Using a fiber array spectral translator device, Raman scattered photons and plasma reflected photons are collected. The device comprises a two dimensional non-linear array of optical fibers drawn into a one dimensional fiber stack that converts a two-dimensional field of view into a curvilinear field of view, wherein the one dimensional fiber stack is coupled to an entrance slit of an imaging spectrometer. The Raman scattered photons, produced by the target area, are analyzed using Raman spectroscopy to produce a plurality of spatially resolved Raman spectra. The plasma emitted photons, produced by the target area, are analyzed using laser induced breakdown spectroscopy to produce a plurality of spatially resolved atomic spectra. A fusion algorithm is applied to at least two of the following to identify one or more chemical compounds in the target area: the plurality of spatially resolved near infrared spectra, the plurality of spatially resolved Raman spectra and the plurality of spatially resolved atomic spectra.
The accompanying drawings, which are included to provide further understanding of the disclosure and are incorporated in and constitute a part of this specification, illustrate embodiments of the disclosure and, together with the description, serve to explain the principles of the disclosure.
In the drawings:
Reference will now be made in detail to the embodiments of the present disclosure, examples of which are illustrated in the accompanying drawings. Wherever possible, the same reference numbers will be used throughout the drawings to refer to the same or like parts.
With reference to
The femtosecond Nd:YAG laser results in femtosecond Raman scattered photons. These photons may provide enhanced S/N through the minimization of non-specific broadband fluorescence and luminescence. Most femtosecond Raman techniques thus far have been based on a pump-probe approach. Femtosecond Raman scattered photons will be measured using a conventional single pulse arrangement with appropriate filters to block broadband femtosecond response.
In addition to enhanced Raman, high intensity femtosecond lasers bring unique benefits to LIBS detection of explosives. The ultrashort LIBS plasma liberates only nanometer thicknesses of material, providing selectivity of surface contaminants from underlying material. Far less thermal plasma is created, reducing the background Planckian emission that is concurrent with species-specific spectral line emission. The unusual phenomena of self-channeling that transforms the diverging (or focused) laser beam into a ˜100 μm diameter self-sustaining waveguide can project breakdown energy densities to distances of a kilometer or more.
In still another embodiment, the illumination system further includes a broad band light source 105 and a beam steering mirror 107. The broad band light source illuminates the sample in the target area with broadband light producing photons reflected from different locations on or within the unknown sample. The stirring mirror 107 functions to change the type of illumination source, from the laser light source 106 to the broad band light source 105. The laser light source 106 and broadband light source 105 are responsive to first control signals generated by processor 160, that control selection and operation of the laser light source 106 and the broadband light source 105.
Referring to
With reference to
The video capture device 124 includes a color video CCD used as a detector. This sensor provides a high fidelity digital image, typically 480 pixel×640 pixel format, and a rapid frame rate, 30 Hz. The video capture device 124 may use ambient light or light from laser light source 106 to illuminate the target area. The video capture device 124 may also collect a series of small images, that are recombined into a larger, macro-image for analysis. The video capture device 124 operates in the first order targeting mode to rapidly screen objects based on the intrinsic size, shape and color properties of the particles. Regions of interest suspected to possess explosive residues are located and identified, honing in on the target area at which to conduct further analysis using LIBS/Raman imaging spectroscopy that provide greater specificity.
In another embodiment, the video capture device 124 includes a liquid crystal tunable filter 120 to sequentially filter the photons detected by the device. In yet another embodiment, the first order targeting system includes a near infrared capture device 122 that outputs an image of the target 150. The near infrared capture device 122 uses ambient light as its light source to illuminate the target area.
The second optical system includes telescope 114, objective 126, beam splitter 128, filter 130, laser line filter 142 and lens 144. Objective 126 collects and focuses luminescence emitted photons, reflected photons, scattered photons and plasma emitted photons and directs the collected photons to beam splitter 128. The second optical system is responsive to second control signals that enable beam splitter 128 to direct the photons to filter 130 or the fiber array spectral translator device 148. Beam splitter 128 directs the collected luminescence emitted photons and collected reflected photons to filter 130. Beam splitter 128 directs the collected scattered photons and collected plasma emitted photons to fiber array spectral translator device 148. Prior to the fiber array spectral translator device 148, the collected scattered photons and collected plasma emitted photons pass through laser line filter 142 which filters out elastic scattered illumination light laser light source 110. Filter 142 enables spectrally filtering of the photons at the illuminating wavelength. The collected scattered photons and collected plasma emitted photons pass through lens 144 which focuses the collected photons onto the entrance of the fiber array spectral translator device 148.
Filter 130 is responsive to third control signals generated by processor 160, wherein the third control signals establish predetermined wavelength bands passed by filter 130. In one embodiment, filter 130 sequentially filters collected luminescence emitted photons, in each of a plurality of predetermined wavelength bands. In another embodiment, filter 130 sequentially filters collected reflected photons, in each of a plurality of predetermined wavelength bands. In yet another embodiment, filter 130 sequentially filters collected luminescence emitted photons and collected reflected photons in each of a plurality of predetermined wavelength bands. Filter 130 includes electro-optical tunable filters, liquid crystal tunable filter (“LCTF”) or acousto-optical tunable filter (“AOTF”). The plurality of predetermined wavelength bands include specific wavelengths or ranges of wavelengths. In one embodiment, the predetermined wavelength bands include wavelengths characteristic of the sample undergoing analysis. The wavelengths that can be passed through tunable filter 130 may range from 200 nm (ultraviolet) to 2000 nm (i.e., the far infrared). The choice of tunable filter depends on the desired optical region and/or the nature of the sample being analyzed. Filter 130 includes a Fabry Perot angle tuned filter, an acousto-optic tunable filter, a liquid crystal tunable filter, a Lyot filter, an Evans split element liquid crystal tunable filter, a Solc liquid crystal tunable filter, a spectral diversity filter, a photonic crystal filter, a fixed wavelength Fabry Perot tunable filter, an air-tuned Fabry Perot tunable filter, a mechanically-tuned Fabry Perot tunable filter, and a liquid crystal Fabry Perot tunable filter. The tunable filer is selected to operate in one or more of the following spectral ranges: the ultraviolet (UV), visible, near infrared, and mid-infrared.
Filter 130 passes photons to a two dimensional array of detection elements. In one embodiment, filter 130 passes luminescence emitted photons to a first two-dimensional array of detection elements 140 (“first detector”). The first detector 140 detects in a spatially accurate manner photons passed by the filter which were luminescence emitted from different locations on or within the unknown sample and generates at least one of plurality of spatially resolved fluorescence spectra and a plurality of spatially accurate wavelength resolved fluorescence images. In a second embodiment, filter 130 passes reflected photons to an infrared two-dimensional array of detection elements 132 (“infrared detector”). The infrared detector 132 detects in a spatially accurate manner photons passed by the filter which were reflected from different locations on or within the unknown sample and generates a plurality of spatially accurate wavelength resolved infrared images.
In another embodiment, filter 130 passes luminescence emitted photons and reflected photons to steering mirror 136. Fourth control signals establish which detector the steering mirror 136 directs the luminescence emitted and reflected photons. In response to the fourth control signals, steering mirror 136 directs the luminescence emitted photons to lens 134 which collects and directs the luminescence emitted photons to the first detector 132. Alternatively, steering mirror 136 directs the reflected photons to lens 138 which collects and directs the reflected photons to the infrared detector 140, in response to the fourth control signals.
The first detector 132 and infrared detector 140 may include a digital device such as an image focal plane array (“FPA”) or CCD or CMOS sensor. The optical region employed to characterize the sample of interest governs the choice of two-dimensional array detector. For example, a two-dimensional array of silicon charge-coupled device (“CCD”) detection elements can be employed with visible wavelength fluorescence for first detector 132. Gallium arsenide (GaAs) and gallium indium arsenide (GaInAs) FPA detectors can be employed for image analyses at near infrared wavelengths for the infrared detector 140. The choice of such devices depends on the type of sample being analyzed. The first detector 132 detects, in a spatially accurate manner, the luminescence emitted photons passed by filter 130. In one embodiment, each detection element in the first two-dimensional array of detection elements used to form the detection array 132. The infrared detector 140 detects, in a spatially accurate manner, the reflected photons passed by filter 130. In one embodiment, each detection element in the first detector 132 and the infrared detector 140 is used to form the detection array.
In another embodiment, the first detector 132 and the infrared detector 140 produce digital images of the entire view of the sample as processed by filter 160.
Fiber array spectral translator device 148 (“FAST”) receives the collected scattered photons and collected plasma emitted photons. With reference to
Referring to
A second two-dimensional array of detection elements 152 (“second detector”) is optically coupled to the spectrograph 150 to detect the plurality of spatially resolved Raman spectra and the plurality of spatially resolved atomic spectra produced by spectrograph 150. In one embodiment, the second two-dimensional array of detection elements 152 comprises a TE-cooled ICCD. Cooling the ICCD reduces the thermal electronic noise associated with the detector to enable the detection of the relatively weak Raman light emitted from the sample
Photodiode 165 is optically coupled to the first optical system and generates a gating signal to synchronize the acquisition time of the second two dimensional array of detection elements with a pulse width of the laser light emanating from the laser light source 110. The photodiode 205 is positioned at the exit of the telescope 114 and triggers a delay and gate generator. This removes timing errors, which can be caused by laser Q-switch jitter, different cable lengths and/or induced noise. The acquisition time, gate width, is then set to match the laser pulse width. Raman scattered photons are only generated while the laser pulse interacts with the sample surface, as Raman scattering has no measurable “lifetime.” The delay time is then set to match the range at which data is collected, twice the distance from the sample divided by the speed of light.
Still referring to
In one embodiment, system 100 operates in a luminescence emitted mode, a Raman spectroscopy mode and a laser induced break down spectroscopy mode. In another embodiment, system 100 operates in a near infrared mode, a Raman spectroscopy mode and a laser induced break down spectroscopy mode. In yet another embodiment, system 100 operates in a luminescence emitted mode, a near infrared mode, a Raman spectroscopy mode and a laser induced break down spectroscopy mode.
In the luminescence emitted mode, the first control signals control operation of the laser light source in order to produce luminescence emitted photons from different locations on or within the unknown sample. The second control signals control the operation of the second optical system such that the second optical system directs the collected luminescence emitted photons to the filter. The third control signals control operation of the filter such that the filter sequentially filters collected luminescence emitted photons, in each of a plurality of predetermined wavelength bands. The fourth control signals such that a steering mirror directs the luminescence emitted photons to the first two dimensional array of detection elements.
In the near infrared mode, the first control signals control operation of the broadband light source in order to produce photons reflected from different locations on or within the unknown sample. The second control signals control the operation of the second optical system such that the second optical system directs the collected reflected photons to the filter. The third control signals control operation of the filter such that the filter sequentially filters collected reflected photons, in each of a plurality of predetermined wavelength bands. The fourth control signals such that a steering mirror directs the reflected photons to the infrared two dimensional array of detection elements.
In the luminescence mode and near infrared mode, the regions of interest are rapidly scanned for target areas, thereby greatly reducing the time to positively identify target analytes. Although explosive materials are not fluorescent, fluorescent contaminates/byproducts produce luminescence emitted photons. The presence of this fluorescent contamination may be used to rapidly pinpointing a target area for further investigation. Near infrared imaging provides a means for screening for surface/subsurface target areas and unknown materials.
To demonstrate the feasibility of utilizing a luminescence emitted mode for the detection of residual explosives, military grade C4 explosive was placed on a human hand,
With reference to
In the Raman mode, the first control signals control operation of the laser light source in order to produce scattered photons from different locations on or within the unknown sample. The second control signals control the operation of the second optical system such that the second optical system directs the collected scattered photons to the fiber array spectral translator device.
The capability to provide highly specific signatures from representative explosive materials in the Raman mode is illustrated in
In the Raman mode, Raman imaging spectroscopy is used as a tool for molecular identification. Explosive materials have strong, unique Raman spectra that are “fingerprints” of the vibrational spectrum of the molecule. This mode differentiates between two very similar molecules, and to differentiate between a target analyte and it's matrix. Using the fiber array translator device provides low pixel fidelity spatially resolved Raman dispersive spectral images and improved reliability of detecting target analytes from a deposited mixture of particles.
In the LIBS mode, the first control signals control operation of the laser light source in order to produce plasma emitted photons from different locations on or within the unknown sample. The second control signals control the operation of the second optical system such that the second optical system directs the collected plasma emitted photons to the fiber array spectral translator device.
System 100 further includes instructions executable by at least one processor that applies a fusion algorithm to two or more data types including spatially resolved fluorescence spectra, the plurality of spatially resolved Raman spectra and the plurality of spatially resolved atomic spectra, in order to identify the unknown sample. In one embodiment, the multiple data types are fused and then searched relative to a signature library or Data Fusion Then Search. As illustrated in
Results from the Data Fusion Then Search (DFTS) approach are shown in
In the case of mixture unknown, the search is performed using a spectral unmixing metric that compares a plurality of spectra for the unknown to library spectra. A spectral unmixing metric is disclosed in U.S. patent application Ser. No. 10/812,233 entitled “Method for Identifying Components of a Mixture via Spectral Analysis,” filed Mar. 29, 2004 which is incorporated herein by reference in its entirety.
The system of the present disclosure may be used to identify unknown materials located above the ground. An above ground area is surveyed to identify a region of interest based on at least one of size, shape and color of the region of interest. The region of interest is illuminated with a plurality of photons producing emitted photons from the region of interest. The emitted photons, produced by the region of interest, are analyzed using fluorescence spectroscopy to produce at least one of the following: a plurality of spatially resolved fluorescence spectra and a plurality wavelength resolved fluorescence images. To identify a target area, one or both of the plurality of spatially resolved fluorescence spectra and the plurality wavelength resolved fluorescence images are used. The target area is then illuminated with a plurality of photons producing Raman scattered photons and plasma emitted photons from the target area. Using a fiber array spectral translator device, Raman scattered photons and plasma emitted photons produced by the target area are collected. The fiber array spectral translator device comprises a two dimensional non-linear array of optical fibers drawn into a one dimensional fiber stack that converts a two-dimensional field of view into a curvilinear field of view, wherein the one dimensional fiber stack is coupled to an entrance slit of an imaging spectrometer. The Raman scattered photons, produced by the target area, are analyzed using Raman spectroscopy to produce a plurality of spatially resolved Raman spectra. The plasma emitted photons, produced by the target area, are analyzed using laser induced breakdown spectroscopy to produce a plurality of spatially resolved atomic spectra. To identify one or more chemical compounds in the target area, a fusion algorithm is applied to at least two of the following: the plurality of spatially resolved fluorescence spectra, the plurality of spatially resolved Raman spectra and the plurality of spatially resolved atomic spectra.
The system of the present disclosure may be used to identify unknown materials located under the ground. A below ground area is surveyed to identify a region of interest based on at least one of size, shape and color of the region of interest. The region of interest is illuminated with a plurality of photons producing reflected photons from the region of interest. The reflected photons, produced by the region of interest, are analyzed using near infrared spectroscopy to produce a plurality wavelength resolved near infrared images. To identify a target area, one or both of the plurality of spatially resolved near infrared spectra and the plurality wavelength resolved near infrared images are used. The target area is then illuminated with a plurality of photons producing Raman scattered photons and plasma emitted photons from the target area. Using a fiber array spectral translator device, Raman scattered photons and plasma emitted photons produced by the target area are collected. The fiber array spectral translator device comprises a two dimensional non-linear array of optical fibers drawn into a one dimensional fiber stack that converts a two-dimensional field of view into a curvilinear field of view, wherein the one dimensional fiber stack is coupled to an entrance slit of an imaging spectrometer. The Raman scattered photons, produced by the target area, are analyzed using Raman spectroscopy to produce a plurality of spatially resolved Raman spectra. The plasma emitted photons, produced by the target area, are analyzed using laser induced breakdown spectroscopy to produce a plurality of spatially resolved atomic spectra. To identify one or more chemical compounds in the target area, a fusion algorithm is applied to at least two of the following: the plurality of spatially resolved fluorescence spectra, the plurality of spatially resolved Raman spectra and the plurality of spatially resolved atomic spectra.
The present disclosure may be embodied in other specific forms without departing from the spirit or essential attributes of the disclosure. Accordingly, reference should be made to the appended claims, rather than the foregoing specification, as indicating the scope of the disclosure. Although the foregoing description is directed to the preferred embodiments of the disclosure, it is noted that other variations and modification will be apparent to those skilled in the art, and may be made without departing from the spirit or scope of the disclosure.
Treado, Patrick J., Nelson, Matthew P., Neiss, Jason, Hubble, II, Hugh W.
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